1. Field of the Invention
The present invention relates to an image generating apparatus, and more particularly, it relates to an image generating apparatus comprising a heat radiating member radiating heat generated in a print portion.
2. Description of the Background Art
An image generating apparatus comprising a heat radiating member radiating heat generated in a print portion is known in general, as disclosed in each of Japanese Patent No. 3005916, Japanese Patent Laying-Open No. 9-188027 (1997), Japanese Utility Model Registration No. 2607240 and Japanese Patent Laying-Open No. 2001-322304.
The aforementioned Japanese Patent No. 3005916 discloses a thermosensitive recording apparatus (image generating apparatus) comprising a radiator plate (heat radiating member) mounted on a thermal head (print portion), a platen roller, a pressing member pressing a rear surface of the radiator plate so as to bring the thermal head into pressure contact with the platen roller, and a pressure releasing lever having a cam shaped portion separating the thermal head from the platen roller. In the thermosensitive recording apparatus described in Japanese Patent No. 3005916, the cam shaped portion of the pressure releasing lever rotates about the platen roller functioning as an axis of rotation so that the thermal head in pressure contact with the platen roller is pressed in a direction opposite to a pressure contact direction with the cam shaped portion presses and the thermal head is separated from the platen roller. No rotating shaft is provided on the radiator plate mounted on the thermal head.
The aforementioned Japanese Patent Laying-Open No. 9-188027 discloses a thermal transfer printer (image generating apparatus) comprising a radiator fin (heat radiating member) mounted on a thermal head (print portion), a platen roller, and a head arm rotatable in a direction in which the thermal head is brought into pressure contact with or separated from the platen roller. In the thermal transfer printer described in Japanese Patent Laying-Open No. 9-188027 (1997), the head arm rotates about a round shaft provided on an end of the head arm as an axis of rotation
The aforementioned Japanese Utility Model Registration No. 2607240 discloses a thermal printer (image generating apparatus) comprising a heat sink (heat radiating member) mounted on a thermal head (print portion), a platen (platen roller), a head pressing spring pressing the thermal head against the platen, a bush mounted on an end of the heat sink, a head up lever rotating the heat sink about the bush as an axis of rotation so as to separate the thermal head from the platen. In the thermal printer described in Japanese Utility Model Registration No. 2607240, the bush functioning as the axis of rotation regulates movement of the thermal head generated with force pressing the thermal head against the platen and force in a transport direction for a paper in printing.
The aforementioned Japanese Patent Laying-Open No. 2001-322304 discloses a thermal printer (image generating apparatus) comprising a radiator plate (heat radiating member) mounted on a thermal head (print portion), a platen (platen roller), a coil spring pressing a thermal head against a platen, and a shaft portion as an axis of rotation of a radiator plate rotating so as to bringing the thermal head into pressure contact with the platen separate or separating the thermal head from the platen. In the thermal printer described in Japanese Patent Laying-Open No. 2001-322304, the shaft portion functioning as the axis of rotation regulates movement of the thermal head generated with force pressing the thermal head against the platen and force in a transport direction for a paper in printing.
In the thermosensitive recording apparatus described in the aforementioned Japanese Patent No. 3005916, however, the radiator plate is rotated with pressing force pressing from the rear surface of the radiator plate with the pressing member and pressing force pressing from a from surface of the radiator plate with the cam shaped portion. In this case, no rotating shaft is provided on the radiator plate and hence the radiator plate can not be stably rotated. Consequently, the thermal head can not be disadvantageously stably brought into pressure contact with or separated from the platen roller.
The thermal transfer printer described in the aforementioned Japanese Patent Laying-Open No. 9-188027, the head arm rotates about the round shaft provided on the end of the head arm as the axis of rotation, and hence the round shaft must be separately mounted on the head arm. Thus, the number of components of the shaft portion is disadvantageously increased due to the separately required round shaft.
In the thermal printers described in the aforementioned Japanese Utility Model Registration No. 2607240 and Japanese Patent Laying-Open No. 2001-322304, the bush and the shaft portion functioning as the axes of rotation respectively regulate the movement of the thermal head in printing and hence the bush and the shaft portion each must have both a function as the axis of rotation and a function of regulating the movement of the thermal head in printing. Thus, the bush and the shaft portion as the axes of rotation must be disadvantageously formed with high accuracy.